Deluxe version of file compressor with optimizations based on file type. Long a staple of the Mac community, it still serves its purpose though handling a large number of off-platform formats, and thus useful for collaboration with non-Mac users.

Installs Kernel Extensions...BEWARE...imho this is is poorly implemented and also can render the OS unstable. Other notable (crap/unstable) progs that do this (thus threatening the stability of the OS) include Norton Utility Suite.
Back to Deluxe, the SYSprefs pane checkbox that enables the creation of archives on the fly as you change the extension in the finder is the problem here (I left mine unchecked when I used to use this app). If you allow this prog access to the OSX kernel, you're risking the OS crashing (not just the prog....the whole OS).

Instead of Deluxe, use the freeware Unarchiver for most files, and the free standalone Stuffit Expander 10 for the few .sitx files you have.
To create archives use the osx built in CMI "create archive off...".

In short, this program is fast becoming obselete.
Stay clear of Deluxe if you want a stable OS